A British U.N. envoy said Wednesday that a thorough investigation indicated that Russia was behind the attempted assassination of a former Russian spy in an English town.

"On the 4th of March, a weapon so horrific that it is banned from use in war was used in a peaceful city in my country," British Deputy U.N. Ambassador Jonathan Allen told Security Council members, referring to an attack using a chemical weapon. "This was a reckless act, carried out by people who disregard the sanctity of life, who are indifferent if innocents are caught up in their attacks."

Former Russian spy Sergei Skripal and his daughter, Yulia, were found unconscious on a park bench in Salisbury and were rushed to a hospital, where they remain in serious condition. Several other individuals, including a police officer, were sickened.

Police tape and bagged items are seen near an inflatable structure in the courtyard of Ashley Wood Recovery; where emergency services worked following the poisoning of former Russian intelligence officer Sergei Skripal and his daughter Yulia; in Salisbury, Britain, March 14, 2018.

Soviet origins

British officials said the chemical nerve agent known as Novichok was used in the attack. It was developed by the Soviet Union and inherited by Russia.

"This was no common crime," Allen said. "It was an unlawful use of force."

He noted Russia has a history of state-sponsored assassinations and cited the 2006 slaying of former Russian spy Alexander Litvinenko, who was poisoned and later died in London.

"Russia has shown in its repeated protection of [Syrian President Bashar al-] Assad's chemical weapons use that it has different standards when it comes to the use of these terrible substances," Allen said. "We have not jumped to conclusions. We have carried out a thorough, careful investigation, which continues."

He said his government had asked the Organization for the Prohibition of Chemical Weapons, headquartered at The Hague, to independently verify the nerve agent used.

"We have offered Russia the chance to explain, but Russia has refused. We have therefore concluded that the Russian state was involved, and we have taken certain measures in response," the British envoy said.

Britain's Prime Minister Theresa May addresses the House of Commons on her government's reaction to the poisoning of former Russian intelligence officer Sergei Skripal and his daughter Yulia in Salisbury, in London, March 14, 2018.

​Expulsion of diplomats

Earlier Wednesday, British Prime Minister Theresa May announced several reprisals, including the expulsion of 23 Russian diplomats from Britain. Russia's Foreign Ministry said in a statement that its response to the measures "will not be long in coming."

"Let me make one thing clear from the very beginning: The United States stands in absolute solidarity with Great Britain," U.S. Ambassador Nikki Haley told the council. "The United States believes that Russia is responsible for the attack on two people in the United Kingdom using a military-grade nerve agent."

Haley's remarks were the strongest from a Trump administration official on Moscow's potential involvement in the incident. She went on to say that Russia "must account for its actions."

He demanded that London provide samples of substances used in the attack for a joint investigation, since Britain claimed they were Russian in origin.

"We stand ready for such an investigation," Nebenzia said. "We have nothing to fear. We have nothing to hide."

The Russian envoy said his government had ceased developing chemical weapons in 1992 and had destroyed its stockpiles in September 2017.

Nebenzia said that in order for the British to determine the agent used was Novichok, they would have to possess a sample for comparison.

"In other words, if the U.K. is so firmly convinced this is the Novichok gas, then that means that they have the samples of this, and they have the formula for this, and they are capable of manufacturing that," the Russian envoy said.

Police officers wear protective suits inside the fence of "Ashley Wood Recovery", a vehicle recovery business in Salisbury, near where the car of Sergei Skripal was taken on March 13, 2018.

Other council members expressed concern about the attack, condemning the use of chemical weapons by anyone at any time. A spokesperson for U.N. Secretary-General Antonio Guterres said the use of nerve agents by a state would constitute a serious violation of international law.

"While the secretary-general is not in a position to attribute responsibility, he strongly condemns the use of any nerve agent or chemical weapons and hopes the incident will be thoroughly investigated," the spokesperson said.